Lemma 2.5 [1]}

Let \({\bf p}\)  be a regular point of the mapping
\(m_{d,G}\) , and let \(m_{d,G}({\bf p})\)  be a smooth point
of \(M_{d,G}\) . Then the set of equilibrium stresses
for \((G,{\bf p})\)  equals the set of normal vectors
to \(M_{d,G}\)  at \(m_{d,G}({\bf p})\) .

